This invention relates to fire protection sprinkler arrangements and, more particularly, to sprinkler arrangements utilizing very extra large orifice (VELO) sprinklers for extended coverage ordinary hazard (ECOH) applications.
The National Fire Protection Association (NFPA) promulgates standards for automatic fire sprinkler systems of various types and categories of protected materials including those designated as ordinary hazards (OH). Extended coverage (EC) sprinklers are intended for use to cover areas of 16xe2x80x2 by 16xe2x80x2 up to 20xe2x80x2 by 20xe2x80x2 per sprinkler. For such applications the water distribution density over the area to be protected should be substantially uniform in order to obtain the best protection. Certifying organizations such as Underwriters Laboratories, Inc. and Factory Mutual Research Corporation conduct tests to determine whether sprinklers satisfy requirements of the NFPA standards in accordance with established procedures. Among the most difficult requirements to satisfy are uniformity of distribution at spacings of 3xe2x80x2 and 7xe2x80x2 6xe2x80x3 below the sprinklers for ECOH sprinklers intending to cover areas of 16xe2x80x2 by 16xe2x80x2, 18xe2x80x2 by 18xe2x80x2 and 20xe2x80x2 by 20xe2x80x2.
The size of the passage opening or xe2x80x9corificexe2x80x9d in a sprinkler body through which the water passes determines, together with the water pressure, the rate at which water is applied to the areas to be protected. A one-half inch orifice has been called a xe2x80x9cstandardxe2x80x9d orifice; a five-eighths inch orifice is called an xe2x80x9cextra largexe2x80x9d orifice, and an eleven sixteenths inch or larger orifice has been designated a xe2x80x9cvery extra large orificexe2x80x9d (VELO). Such sprinklers have nominal K factors, corresponding to the flow rate in gallons per minute divided by the square root of the water pressure, of 5-xc2xd, 11 and 14 or more, respectively. The water distribution pattern produced by a sprinkler depends to a large extent on the arrangement of the deflector against which the water is directed when it emerges from the orifice.
The Meyer et al. U.S. Pat. Nos. 5,366,022 and 5,579,846 disclose ECOH sprinklers having deflectors in the form of a flat or slightly angled disc with radial slots of alternately different length extending inwardly from the periphery of the disc. The Meyer et al. U.S. Pat. No. 5,609,211 discloses an ECOH sprinkler having a deflector with a circular periphery and a plurality of radial slots of uniform length extending inwardly from the periphery in an outer region which is bent downwardly at a uniform angle from the central portion of the disc providing a cone angle of about 90xc2x0, i.e., about 45xc2x0 from the horizontal.
The Pounder et al. U.S. Pat. No. 5,862,994 discloses an ECOH sprinkler with a deflector having an inner surface with a recessed central area and a recessed redirecting area surrounding the central area and extending at an angle to the central area and peripheral tines having inner surfaces inclined at different angles to the axis of the sprinkler and also having different widths.
Accordingly, it is an object of the present invention to provide a VELO ECOH sprinkler arrangement which overcomes disadvantages of the prior art.
Another object of the invention is to provide a VELO ECOH sprinkler arrangement producing improved uniformity of distribution of water for extended coverage areas.
A further object of the invention is to provide a fire protection sprinkler arrangement which assures exceptional uniformity of water distribution at 16xe2x80x2 by 16xe2x80x2 to 20xe2x80x2 by 20xe2x80x2 coverage over hazards located at spacings of 3xe2x80x2 and 7.5xe2x80x2 below the sprinkler.
These and other objects of the invention are attained by providing a sprinkler arrangement with a sprinkler body having an axial passage for delivery of water and a deflector supported in spaced relation to the axial passage and disposed generally in a plane extending perpendicular to the axis of the passage in which a peripheral portion of the deflector is bent toward the sprinkler body about a circle and the perimeter of the deflector has chordal segments defined by planes extending substantially parallel to the axis of the sprinkler body. In addition, a plurality of slots extend inwardly from the perimeter of the deflector to a substantially uniform spacing from the axis of the sprinkler defining between them tines of differing length. Preferably the deflector is supported from the sprinkler body by a pair of frame arms disposed in a plane containing the sprinkler axis and includes tines in the plane of frame arms and tines in an axial plane extending perpendicular to that plane which are wider than the other tines and has slots adjacent to those tines which are directed parallel to the plane of the frame arms or to the plane perpendicular thereto.
In a preferred embodiment the sprinkler has a K factor of at least 14 and the deflector has a projected maximum diameter of about 1.66 inches and the spacing between opposed chordal perimeter segments is about 1.51 inches while the radius of the circle at which the deflector periphery is bent downwardly is about 1.35 inches.